Electric burglar-alarm system.



No. 65l,325

(No Model.)

' Patented June 5, I900. J. F. DORSEY.

ELECTRIC BUHGLAR ALARM SYSTEM.

(Application filed Oct. 7, 1899.)

2 Sheets-Sheet l.

V ill/272, 07: a Z W Tn: -omus PETERS 60.. ?HOTO-UTHO., WASHINGTON r;, c

No. 65I,325. Patented lune 5, I900.

J. F. nonsav. ELECTRIC BUBGLAB ALARM SYSTEM.

(Application filed Oct. 7, 1899.)

(No Modei.)

2 Sheets-Sheet 2.

Jhve nfor m: Noam PETERS 00.. PNOTGUTHQ. WASHINGTON. 0. c.

UNITED STATES PATENT Felon.

JOHN F. DORSEY, OF \VASIIINGTON, DISTRICT OF COLUMBIA, ASSIGNOR OF ONE-HALF TO ROBERT G. CALLUM, OF SAME PLACE.

ELECTRIC BURGLAR-ALARM SYSTEM.

SPECIFICATION forming part of Letters Patent N 0. 651,325, dated June 5, .1900.

Application filed October '7, 1899. Serial No. 732,904. tNo model.)

To all whom it may concern:

Be it known that I, JOHN F. DORSEY, a citizen of the United States, residing at Washington, in the District of Columbia, have invented new and useful Improvements in Electric Burglar-Alarm Systems and Apparatus Used Therein, of which the following is a specification.

My invention relates to the class of electric 1o burglar-alarm systems in which a signal or alarm is given at a central office or other distant place whenever an attempt is made to enter the guarded structure. In prior systems of this character each building is :5 equipped with devices, which operate to cut out a resistance whenever a door or window is opened, so that the current of the connecting line will be so varied as to cause a circuitcloserin the form of a galvanometer to close an alarm-circuit at the central office and give an alarm. It will be readily seen that with systems of this character the same alarm will be given by the grounding of the current at any point along the connecting line, and it is therefore not known when an alarm is given whether it is caused by an attempt to enter the guarded structure or by an accidental grounding of the line-current.

The resistance and the devices which are 0 attached to the doors and windows of the protccted structure for cutting said resistance out of the main line are usually arranged within a local circuit adapted to be cut into and out of the main line, so that when used 3 3 for the protection of business establishments the system may be readily connected at night and disconnected d uring business hours,when protection is not required. The main lineis always kept in closed circuit by ground con- 0 nections at each end, and the cutting in or out of this local circuit, which I will term the protecting-circuit, will cause a variation of the galvanometer or circuit-closer at the central station, and in order that the cause .15 of such variation may be known certain signals are first given by parties in the protected building by means of a key or other device. With one familiar with the working of the system it is an easy matter to ground the wire outside of some business establish- .nection removed without detection.

ment just before the closing hour and by the use of a battery and key receive and answer the signals and after the protecting-circuit hasbeen cut into the main line measure its resistance. The proper signal can then be given to the central office and the ground con- The next night the line can again be grounded, the

signals received and transmitted, and a resistance equal to that of the protecting-cir- 6o cuitcut into the line, so that theprotected building will be removed from the system without detection. r

The main object of my invention is to provide means for indicating by a suitable signal or alarm at the central office a short circuit orgrounding of theline-wire outside of the protectedbuilding whenever it occurs,regardless of whether the protecting'circuit is in or out of circuit therewith.

With the systems now in use the alarm-circuit is closed by the galvanometer or circuitcloser when the protecting-circuit, with its resistance, is cut out of the main line, so that any accidental grounding of the latter will not be discovered until it is attempted to place the system in operative condition by cutting in the protecting-circuit. It is then found that the galvanometer will fail to respond and that the system is inoperative. The accidental grounding of the main line is not of infrequent occurrence,and it almost invariably happens that although it may occur early in the day the fact remains undiscovered until some business establishment is 8 5 closing for the night, when it is too late to locate and remedy the difiiculty. At such times watchmen are sent to guard the building until daylight, when the trouble may be more readily located and removed. These 0 defects are remedied by the main feature of my invention, which consists in the employment of circuit-closing contacts controlled by variations in the main-line current for 010s ing separate or branch alarm-circuits, so ad- 5 justed wit-h reference to each other and to a resistance in the main line that the circuit controlled by one set of contacts will remain open after the circuit controlled by the other set has been closed by a short circuit in the loo protecting-circuit and until said resistance has been cut out by a short circuit in the main line, as hereinafter explained in detail.

Another feature of my invention relates to the independent arrangement of the protecting-circuit with reference to the resistance controlled thereby and the division of the protecting-circuit into sections, whereby a short circuit occurring therein may be accurately and quickly located and the other sections remain unaffected thereby.

After a detail description of my invention the features deemed novel will be speci tied in the claims hereunto annexed.

Referring to the drawings, Figure l is a diagrammatic illustration of a system embodying my invention in which two separate circuit-closing instruments are employed in connection with the alarmcircuits. Fig. 2 is a diagrammatic illustration of an alarm-circuit in which a single circuit-closing instrument is employed. Fig. 3, in front view, illustrates another form of circuit-closing instrument and its connections with an alarm-circuit. Fig. t is a central vertical section of the instrument illustrated in Fig. 3, taken on line a: w of said figure; and Fig. 5 is aview of the movable contacts or needles and their armature detached from said instrument.

Referring to Fig. 1, that portion of the system which is located at the central office is inclosed within the dotted line y and that portion located within the protected structure is inclosed within the dotted line It is to be understood that each building under protection of the system is equipped with numerous devices which operate to break or short-circuit an electric current whenever a door or window is opened or an attempt is otherwise made to effect an entrance. In prior systems of this character these devices have been arranged in a single circuit, which is cut into the main circuit, so that each device within the protecting-circuit is directly connected to the central office. In myimproved system the protecting-circuit has no direct connection with the main-line current, and it is divided into sections representing floors or other divisions of the building, and each section is connected with an annunciator, so that when any of the devices therein are operated to break or short-circuit the current the annunoiator will indicate the particular section in which such device is located. The annunciator is arranged to cut out a resistanoe in the mairrline for giving the signal to the central office, as will be explained.

The protecting-circuit A (illustrated in diagram in Fig.1) may be divided into any nu mber of sections; but, as shown, it is divided into two sections a and a. Section at is composed of two wires 1 and 2, connected to 0pposite poles of a local battery (0 and extending therefrom in a parallel course to all windows, doors, and other exposed places of that portion of the building to be covered thereby.

These wires 1 and 2 are connected to an elec-' tromagnetb of an annuneiator B and form a closed circuit through the battery a Between the wires 1 and 2 are arranged any of the well-known devices a, which short-circuit or break the current whenevera door or window is opened, as will be readily understood. The devices (L3 are shown as shorteircuiting devices; but it is to be understood that circuit-breaking devices may be substituted to perform the same service. Section a is similar in all respects to section a, its two wires 3 and at being connected to the same battery a and to an electromagnet b of annunciator B, and it is provided in the same manner with short-circuiting devices a, the only difference between the two sections a and a being that they cover different floors or sections of the protected building. The electromagnets b and I) hold pivoted armatures b b in engagement with annunciatordrops 12 b and away from contacts I) If, connected to the main-line wire D. The armatures b I) are provided with springs b b, tending to draw them away from their magnets and into engagement with the contacts b N, and they are connected to ground 0 by wires 5 and 6, respectively.

The main-line wire D, which connects the central office, is connected to arm c of a twopointed switch E, one point of which is connected by wire 7 to ground C and the other point connected to a resistance F and then to ground 0 by wire 8. Connected to line-wire D is a branch wire 9, to which the contacts I) and 11 are connected by wires 10 and 11, respectively. The line D is connected at the central office to one pole of a battery d, the other pole of which is connected to ground C by wire 12.

When the guarded structure or building is under protection of the system, the arm 6 of switch E is turned in the position shown, so that the main current will pass from said switch through resistance F to ground. It will now be understood that should any of the devices a in the protecting-circuit be operated to short-circuit the section in which it is located the resistance F will be cut out of the main circuit in the following manner: Should, for instance, any of the devices a of section a be operated, the magnet b of the annunciator will be out out of the local circuit and its armature b will be drawn by its spring b into engagement with contact Z) and 'the drop b will at the same time be permitted to fall to indicate that the trouble is in that section of the building covered by section a. The main current will then pass from linewire D through wires 9 and 10 to armature b and then to ground 0 through wire 5. The resistance F will thus be cut out of the mainline circuit and cause a galvanometer at the central office to indicate the fact by closing an alarm-circuit, as will be presently explained. The resistance F will in like manner he cut out of the circuit by the operation of any of the devices a of section a. During the time protection is not desired the arm of the switch E is turned for shifting the main-line current directly to ground through wire 7, the main line being thus always kept in closed circuit, so that any break in the line-wire may be promptly discovered, and also to admit of signals to and from the central office by means of a suitable key. (Not shown.)

Within the main line D at the central office is the usual circuit-closer G, controlled by the main-line currentfor closing a local alarmcircuit whenever resistance F is cut out by a break ora short circuit. This circuit-closer is in the form of a galvanometer, the needle 9 of which forms one terminal of the alarm-circuit, the other terminal of said circuit being connected to two fixed contacts g and giwith which the needle engages when moved in either direction by variations in the mainline current.

The arrangement of the alarm-circuit may be widely varied, and any suitable instrument or instruments may be employed for giving the alarm. In Fig. 1 I show both a bell II and an annunciator I, the latter consisting of a drop 1', retaining-armature t", and electromagnet 41 These are connected in circuit with the circuit-closer G as follows: From battery J a wire 13 connects with bell H, which is connected by wire 14 to fixed contact g, which in turn is connected by wire 15 to fixed contact g Wires 14 and 15 are provided with switches h and h respectively, which are used to open the circuit for preventing a continuous ringing of the alarm when the circuit is closed by the circuit-closer. G. The galvanometer-needle or movable contact g is connected by wires 16 and 17 with the electromagnet t of the annunciator, and the latter is connected by wire 18 with battery J. The alarm-circuit, as thus far described, is in all essential respects the same as that now in use. The needle of the galvanometer G is adjusted to stand midway between the contacts g 9 when the resistance F is in the main line, so that when said resistance is cut out by a short circuit in the protecting-circuit it will be deflected against contact g and close the alarm-circuit,and thus cause the bell II and annunciator I to be operated, as will be understood. If, then, the switch h be opened for breaking the circuit, the latter will still be in readiness to give a second sig nal should a break occur at any point in the main line. Should this occur the galvanometer-needle Q will move to its upright position against contact g and again close the circuit. The switch it may then be used to again open the circuit. When the resistance F is cut out by the switch E, needle Q will move against and remain in contact with contact g but before the switch is operatedsignals are exchanged with the central ofiice, so that the alarm resulting from the cutting out of the resistance F may he understood. These signals are given by the usual key and sounder, (not shown,) or they may be given by successive movements of the switch-arm c.

It will be readily understood that with the system as thus far described should a short circuit occur in the line-wire during the time the resistance F is out of the circuit no alarm or signal will be given, and the fact will remain undiscovered until resistance F is again out into the circuit. It will also be understood that should a short circuit occur in the main line during the time resistance F is in the circuit the same signal will be given as when one of the devices a short-circuits the protecting-circuit. It will therefore not be known whether. such signal is caused by a short circuit in the main line or by an attempt to enter the protected structure. These defects I overcome by providing at. the central station a second circuit-closer similar to that already described. This second circuit-closer is a galvanometer K, arranged within the main-line wire D. The needle 7c is connected bya branch wire 19 to wire 17 of the alarm-circuit already described, and in line with the needle is a fixed contact 70, connected by wire 20 to a bell H,which is in turn connected to battery J by wire 21. A second circuit is thus formed, which includes the battery and annunciator of the other circuit. In order to fulfil intended requirements, the needle 70 of galvanometer K would ordinarily have a much greater range of movement than that of the galvanometer before described, and in order to reduce this movement the needlearmature 10 is weighted, as at 70 to the rear of its line of deflection, so that a greater current will be required for moving it a given distance than would be the case were the needle and armature evenly balanced.

'VVithin the mainline D and just inside of the protected structure is a small resistance K, (shown in the form of a lamp,) which may, if desired, be hid from view by a box or cover, (indicated in dotted lines.) As this resistance is at all times within themain-line circuit, the galvanometer Gis of course adjusted so that this resistance will in no manner i11- terfere with its operation when resistance F is cut out either by the switch E or by the operation of any of the devices a as described. The fixed contact k of galvanometer K is so adjusted with reference to the defiection of needle 76 that the alarm-circuit controlled thereby will be kept open by the resistance K after the resistance F is out ofthe circuit anduntil resistance K is cut out by a short circuit in the main line. It will thus be seen that the alarm controlled by galvanometer K will only be sounded by a short circuit which cuts out resistance K, so that should an alarm be given by the operationof galvanometer G alone it will be positively known that the trouble is within the protected structure, and an inspection of the an- IIO nunciator B will indicate the exact locality. When the galvanometer K is operated to close the circuit controlled thereby, it is positively known that the trouble is caused by a short circuit in the main line outside of the protected structure. The closing of the circuit controlled by galvanometer K causes the sounding of bell H and the operation of a11- nunciator I, as will be readily understood, and to prevent a continuous ringing of the bell wire is provided with a switch 7L2 for opening the circuit.

The two galvanometers G and K may be connected to operate the same alarm; but I prefer to have separate bells readily distinguishable as to sound to indicate the different character of the signals. Whenever two galvanometers are employed in the same circuit, each must operate through the resistance of the other, and while this may not be objectionable I have embodied the features of the two galvanometers in a single instrument, one form of which is illustrated in Fig. 2 in connection with a single-alarm circuit. The circuit-closing instrument L here shown is in the form of a galvanometer located as before within the main-line wire D. The needle Z is connected by wire 22 with bell H which in turn is connected by wire 23 to one pole of a battery J, the other pole of the battery being connected by wire 24 to fixed contact Z at one side of the needle Z. At the other side of the needle is a spring'contact Z connected by wire 25 to battery J, and at the rear of spring-contact Z is a fixed contact Z connected by wire 26 to fixed contact Z. The line-wire D extends to a guarded structure or building, wired and connected as before described in connection with Fig. 1. When the resistance Fis in the main line, needle Z is held midway between contacts Z and Z and operates to close the circuit in the same manner as the galvanometer G of Fig. 1. When the resistance F is cut out by the operation of any of the devices in the protecting-circuit or by the switch E, the needle Z will be deflected against spring-contact Z and close the alarm-circuit, and should a break occur in the controlling-circuit the needle will be moved to contactl, in either case causing an alarm to be given. Switches h and h are provided in wires 24 and 25, respectively, to open the circuit after it has been closed by either of the causes mentioned. When resistance F is out of the main line, the needle Z will rest against contact Z which is made quite delicate, so that it may be easily moved by the needle should the current of the main line he in any manner sufficiently increased. In this condition the alarm-circuit is opened by the switch h to prevent a continuous ringing of the alarm. Fixed contact Z is adjusted to be slightly removed from spring-contact Z when resistance F is out of the main-line circuit. Should a short circuit occur to cut out resistance K, spring-contact Z will be moved by the needle Z to fixed contact Z and a circuit will be completed through all of the contacts, the current then passing from battery J through wire 24: to contact Z, through wire 26, contacts Z and Z needle Z, wire 22, bell H back to battery J through wire 23, the switch in wire 25 being open, as already explained.

In Figs. 3, 4, and.5 I show another form of circuit-closing device in the form of a galvanometer having two armatures and two needles operating as separate movable contacts. The needle m, with its armature m, is pivotally mounted in the usual manner within the coil M, the latterbeing wound upon a spool or frame M. The needle 9?. is attached to an armature n, pivotally mounted in suitable bearings above the armature m, and has a central opening n through which the needle m projects, the two armatures, with their needles, being thus permitted to vibrate independently of each other. Mounted upon the frame M and between the two needles m and n and parallel with their line of motion is a plate or standard 0, having slots 0 and 0 in which the electrical contacts p, p, and 19 are adjustably mounted. Contacts 1) and p are mounted in slot 0' at each side of the needle m and in the path of its travel. Contact 19 is mounted in slot 0 in line with the path of needle n, the latter being bent through said slot to bring its tip to the front of the plate 0, as clearly shown. Both needles of this instrumentare controlled by the coil M, through which the main-line current passes, as in the other instruments before described. The movable and fixed contacts are coupled to the alarm-circuit as follows: Connected with one pole of a battery J is a wire 27, leading to hell H and from hell H a wire 28 connects with both of the movable contacts or needles m and n. This wire 28 is connected to a binding-post q, Fig. 4., from which a wire 29 connects to a screw 30, secured in the frame m supporting the armature m. From this point the electrical connection to the needle m is through frame m to the armature-shaft m through wire 31 to needle on. The connection from screw to needle n is through wire f 32 to bearing-plate n to armature-shaft 02 through wire 33 to needle 11.. The supporting-shafts of both armatures are mounted in insulating-blocks, as clearly shown. From the other pole of battery J 2 a wire 34 leads to fixed contact 1), which is connected by wire 35 to fixed contact 19 A second wire 36 leads from the same battery-pole to fixed contact 13. The wires 34, 36,and 35 are each provided with switches h h 72, for opening the circuit, as before described. The operation of needle min connection with fixed contacts 13 and p is the same as the needle of galvanolneter G of Fig. 1, and the operation of needle 1?. in connection with its fixed contact p is the same as that of galvanometer K of Fig. 1, and each needle, with its fixed contacts, may be coupled in separate circuits instead of the single circuit shown. The movable contacts m and n are shown in the position they occupy when the resistance F is in the main-line circuit, and they both move together when said resistance is cut out, and needle at will then complete the alarm-circuit by coming in contact with fixed contact 1); but needle 7t will be held by resistance K away from its fixed contact 10 and until said resistance is cut out by a short circuit outside of the protected building. When resistance F is out of the main line, needle m will rest against contact 19' and needle n will be separated by a short space from contact 132. The alarm-circuit being closed by the needle m it is opened at switch h. Should the main line then become:short-circuited, resistance K will be cut out and needle 12 deflected against contact 13 and give the alarm. The armature n of needle n is weighted, as at 91 to lessen its range of movement, as explained in connection with galvanometer K of Fig. 1.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. In a burglar-alarm system the combination of a normally-closed main line connecting an alarm-station with a structure to be protected, circuit-closing devices operated by an increase in the current of the main line for closing separate or branch alarm-circuits, and a resistance for controlling one of said circuit-closers independently of the operation of the other, substantially as described.

2. In a burglar-alarm system the combination with a normally-closed main line connecting an alarm-station with a structure to be protected, of a resistance normally within said main line, a protecting-circuit within the protected structure independent of the main circuit, and means whereby a break or short circuit in the protecting-circuit will operate to out said resistance out of the main line, substantially as described.

3. In a burglar-alarm system the combination of a normally-closed main line connecting an alarm-station wit-h a structure to be protected, a resistance adapted to be cut into or out of circuit therewith, a protecting-circuit consisting of separate local circuits each independent of each other and of the main line, an annunciator to which each of said local circuits is connected, and means whereby a short circuit or break in any of said local circuits will operate through said annunciator to cut out said resistance, substantially as described.

4. In a burglar-alarm system, the combination of a normally-closed main line connecting an alarm station with a structure to be protected, a resistance normally within said main line, a protecting-circuit consisting of separate local circuits each independent of each other and of the main line, electroinagnets in each of said local circuits, armatures controlled by said magnets, and contacts connected to the main-line circuit adapted to be engaged by said armatures when released by said magnets for grounding the main line and cutting out said resistance, substantially as described.

5. In a burglar-alarm system, the combination of a normally-closed main line connecting an alarm-station with a structure to be protected, circuit-closing contacts controlled by variations in the condition of the main-line current for closing separate or branch circuits, a resistance adapted to be cut into or out of said main line, a protecting-circuit provided with devices for cutting said resistance out of the main-line circuit, and a second resistance in the main line for controlling the movement of one set of contacts independently of the other, substantially as described.

6. In a burglar-alarm system the combination of a normally-closed mainline connecting an alarm-station with a structure to be protected, a resistance adapted to be cut into or out of circuit therewith, circuit-closing contacts controlled by variations in the main-line current for closing an alarm-circuit when said resistance is cut out, a second set of contacts also controlled by variations in the main-line current for closing a separate or branch alarmcircuit, and a second resistance in the main line for preventing the closing of said second set of contacts when said first-mentioned resistance is cut out, substantially as described;

7. In a burglar-alarm system the combination of a normally-closed main line connecting an alarm-station with a structure to be protected, a resistance adapted to be cut into or out of circuit therewith, a protecting-circuit in the guarded structure provided with means for cutting out said resistance, a second resistance inthe main line, separate sets of contacts controlled by variations in the mainline current for closing separate or branch alarm-circuits so adjusted with reference to each other and to said second resistance, that the circuit controlled by one set of contacts will remain open after the circuit controlled by the other set of contacts has been closed by the cutting out of the first-mentioned resistance, substantially as described.

8. In a circuit-closing instrument adapted to be controlled by Variations in the condition of an electric current, the combination of a coil, a pair of armatures pivotally mounted within said coil independently of each other, contacts carried by each armature, and adjustable contacts mounted in the path of the before-mentioned contacts, substantially as described.

IIO

said coil, an adjustable contactin the path of In testimony whereof I have hereunto set said movable contact, a, second movable conmy hand in presence of two subscribing witto tact also consisting of an armature and neenesses.

dle pivotally mounted Within said coil and an adjustable contact in the path thereof, one of said movable contacts being weighted at one Vitnesses: side opposite to the adjustable contact with I HOWELL BARTLE, which it engages, substanLially as described. PHILIP F. LARNER.

JOHN F. DORSEY. 

